1. Field of the Invention
The present invention relates to continuous ink jet printers of the kind having plurality of ink supply and circulation subsystems (e.g. to enable different color ink printing) and more particularly to constructions for providing selective operation of those systems.
2. Background Art
In continuous ink jet printing apparatus ink is pumped, through a supply line from a supply reservoir, to a print head under sufficient pressure to cause ink streams to issue from the orifices of the print head. Stimulating vibrations are applied to the print head to cause the ink streams to form streams of uniformly sized and spaced droplets, which are electrically controlled into printing or non-printing paths. The non-printing droplets are caught in a catcher device and can be returned to the supply reservoir by a catcher return line, which can be coupled to a main return line.
Continuous ink jet printing systems have been proposed wherein a plurality of discrete orifice arrays cooperate in printing on a common print medium, e.g. to allow the use of different ink colors or to increase printing speed and/or printing resolution. These multi-head systems, in general, utilize separate and completely duplicative ink circulation systems for each separate print head. That is, each circulation system has a separate pump motor and a separate pressure control system.
Our concurrently filed U.S. application Ser. No. 945,265, entitled "Pressure Regulation System for Multi-Head Ink Jet Printing Apparatus" by M. Piatt and K. Houser discloses unique structural and functional approaches for reducing the pressure regulation components in a continuous, multi-head ink jet printer. These approaches also provide performance advantages, e.g. from the viewpoints of accuracy in drop placement and flexibility in drop stimulation. The pressure regulation system described in that concurrently filed application enables a single motor to operate a plurality of ink circulation systems for a continuous, multi-head printer.